If a shake is generated from a lens held by a lens driving device for automatic focus, and the shake correction device of the camera swings the lens or the lens driving device for automatic focus in a direction that is perpendicular to an optical axis direction of the lens to restrain an image formed on the image sensor from shaking or shifting. For example, configurations of shake correction device described in patent document 1 include: a plurality of suspension lines, extending along the optical axis direction; a lens driving device for automatic focus, suspended and supported by the suspension lines so as to swing in the direction perpendicular to the optical axis direction; and an electromagnetic drive unit, having a coil for swinging and a permanent magnet. The shake correction device can restrain the fuzzy of the image by making the lens driving device for automatic focus swing with the lens simultaneously.
FIG. 6 shows a view of a shake correction device 30 of the prior art. FIG. 6(a) is a perspective view of the shake correction device 30, FIG. 6(b) is a perspective view of an electromagnetic drive portion, FIG. 6(c) is an enlarged perspective view of the suspension and support portion. Here, the optical axis direction of the lens which is not shown is set as Z (Z-axis) direction, and the two directions perpendicular to the Z axis are set as X (X-axis) direction and Y (Y-axis) direction.
As shown in FIG. 6, the shake correction device 30 includes: a board like base board 31 having an opening toward the Z-direction in a central portion; four suspension lines 32 extending along the Z direction; four permanent magnets 34 is board shape and held by a side surface 33b of a box shaped magnet holder 33 at the +Z side of the base board 31, and of which magnet pole surfaces are arranged to face the X direction and the Y direction and are disposed around an axis parallel to the Z axis at an interval of 90 degree; the coils 35x for swinging of the X side and the coils 35y for swinging of the Y side which are wound around the Z direction, arranged to be opposite to and have a gap with a surface of the permanent magnets 34 on the −Z side and mounted on the +Z side of the base board 31. Wherein on an inner periphery side of the permanent magnet 34, coil 40 for automatic focus is wound around an outer peripheral side of a lens holder 38, a front spring member 37A coupled to an end surface 33a on the +Z side of the magnet holder 33. The lens driving device for automatic focus is used to generate Lorentz force to shift the lens holder 38 in the Z axis direction. And a shield cover 39 having a circular opening in a center portion is mounted on the outside of the all parts.
As shown in the FIG. 6 (c), one end of each of the four suspension lines 32 is coupled to four corners of the base board 31 respectively. The other end of each of suspension lines 32 is coupled to a line connection portion 37d, the line connection portion 37d forms on an outside holding portion 37b of the front spring member 37A. Thus, the magnet holder 33 can swing along X direction and Y direction and can be supported by the suspension lines 32.
As shown in the FIG. 6 (b), coils 35x for swinging of X side are arranged on the −X side and +X side of the base board 31, coils 35y for swinging of Y side are arranged on the −Y side and +Y side of the base board 31. The lens driving device for automatic focus is swung towards the X direction after the coils 35x for swinging of X side is energized. Moreover, the lens driving device for automatic focus is swung towards the Y direction after the coils 35x for swinging of Y side is energized.
The front spring member 37A and an inside holding portion 37a of a rear spring member which is not shown in the drawings are coupled to the lens holder 38. The front spring member 37A and an arm portion 37c of the rear spring member function as a spring and suspend and support the lens holder 38 so as to move lens holder 38 towards the Z direction. Moreover, the lens holder 38 is swung by the coils 40 for automatic focus, the lens holder 38 suspended and supported by the front spring member 37A and rear spring member function as a lens driving device for automatic focus. The lens holder 38 is shifted towards the Z direction after the coils 40 automatic focus 40 is energized.
Moreover, the shield cover 39 is formed by a strong magnetic conductor or a non-magnetic conductor. The shield cover 39 is a box body with a circular opening portion formed on the surface on the +Z side, and surrounds the +Z side and the periphery side of the Z axis of the shake correction device 30. And the shield cover 39 can shield electromagnetic waves leaked from the outside or emitted from an image sensor.
Further, as shown in FIG. 6 (c), a damping material 41 formed a silicone gel and the like is clamped between the base board 31 and the magnet holder 33. The damping material 41 can suppress unnecessary resonance generated by the shake correction device 30 and improve endurance ability of the shake correction device 30 with respect to drop impact.